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DP83848Q-Q1: Link up time at startup

Tomoaki Yoshida91
Genius 5255 points
Part Number: DP83848Q-Q1

Hi team,

I have a question.

How long does it take from power on to link up completion?

If there is an influence by the Auto Negotiation and Auto MDI/MDI-X, please also tell me the influence value.

Best regards,

Tomoaki Yoshida

  • 0
    TI__Mastermind 19780 points
    Hi Yoshida-san,

    The link up time of the DP83848Q cannot be guaranteed, and is variable based on auto MDIX and auto-negotiation. These times are not a specification of the IEEE standard.

    We have determined that anything longer than 5 seconds is considered abnormal for the DP83848 family.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Genius 5255 points

    Hi Rob-san,

    Thank you for your support.

    I understood that the link up time cannot be guaranteed.

    Please tell me if there are indicators and actual measurement data that link up time will change so much with Auto-negotiation and MDIX.

    Althought you said anything longer than 5 seconds is considered abnormal, how does it behave in that case?

    Please tell me which part of the data sheet is written.

    Best regards,

    Tomoaki Yoshida

  • 0 in reply to Tomoaki Yoshida91
    TI__Mastermind 23675 points
    Hi Yoshida-san,

    Auto-Negotiation relies on handshaking between the DUT and Link Partner. Pages are exchanged during auto-negotiation and this exchange takes time to complete. To further complicate the link-up process, you have Auto-MDIX capability, which will rotate sending out signaling on the TD+/- and RD+/-. Only when there is no collision between the DUT and LP, can a MDI/MDIX configuration be decided. This is what further increases the randomness of the link-up time and makes it extremely difficult to predict.

    A link-up time higher than 5 seconds is abnormal based on our internal testing. It generally means there is an issue with your reference clock.

    Best regards,
    Ross